Add flying dodge mechanic at resolve time

When altitude differs at resolve time (attacker or defender changed flying state during window phase), attack misses. Treated as successful dodge with zero damage.

src/mudlib/combat/encounter.py

@@ -123,6 +123,23 @@ class CombatEncounter:
                 combat_ended=False,
             )
 
+        # Check for altitude mismatch (flying dodge)
+        attacker_flying = getattr(self.attacker, "flying", False)
+        defender_flying = getattr(self.defender, "flying", False)
+        if attacker_flying != defender_flying:
+            # Altitude mismatch - attack misses
+            template = "{attacker}'s attack miss{es} — {defender} {is|is} out of reach!"
+            # Reset to IDLE
+            self.state = CombatState.IDLE
+            self.current_move = None
+            self.pending_defense = None
+            return ResolveResult(
+                resolve_template=template,
+                damage=0.0,
+                countered=True,
+                combat_ended=False,
+            )
+
         # Check if defense counters attack
         defense_succeeds = (
             self.pending_defense